Dense redistribution layers in semiconductor packages and methods of forming the same

ABSTRACT

A method embodiment includes forming a patterned first photo resist over a seed layer. A first opening in the patterned first photo resist exposes the seed layer. The method further includes plating a first conductive material in the first opening on the seed layer, removing the patterned first photo resist, and after removing the patterned first photo resist, forming a patterned second photo resist over the first conductive material. A second opening in the patterned second photo resist exposes a portion of the first conductive material. The method further includes plating a second conductive material in the second opening on the first conductive material, removing the patterned second photo resist, and after removing the patterned second photo resist, depositing a dielectric layer around the first conductive material and the second conductive material.

PRIORITY AND CROSS-REFERENCE

This application claims the benefits of U.S. Provisional ApplicationSer. No. 62/371,620, filed on Aug. 5, 2016, which application is herebyincorporated herein by reference in its entirety.

BACKGROUND

The semiconductor industry has experienced rapid growth due to ongoingimprovements in the integration density of a variety of electroniccomponents (e.g., transistors, diodes, resistors, capacitors, etc.). Forthe most part, improvement in integration density has resulted fromiterative reduction of minimum feature size, which allows morecomponents to be integrated into a given area. As the demand forshrinking electronic devices has grown, a need for smaller and morecreative packaging techniques of semiconductor dies has emerged. Anexample of such packaging systems is Package-on-Package (PoP)technology. In a PoP device, a top semiconductor package is stacked ontop of a bottom semiconductor package to provide a high level ofintegration and component density. PoP technology generally enablesproduction of semiconductor devices with enhanced functionalities andsmall footprints on a printed circuit board (PCB).

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1 through 36 illustrate various intermediary stages of forming asemiconductor device package in accordance with some embodiments.

FIG. 37 through 40 illustrate various intermediary stages of forming asemiconductor device package in accordance with some other embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Various embodiments provide methods of forming conductive features, suchas conductive lines and/or vias, in redistribution layers (RDLs) of asemiconductor package. Although various embodiments are described withrespect to a specific context (e.g., an integrated fan-out (InFO)package having fan-out RDLs), various conductive feature fabricationmethods may be applied to other packages in any area of a device whereconductive features are found. Various embodiments may provide one ormore of the following non-limiting advantages: smaller conductive viasby using a higher resolution photoresist to define a shape of theconductive vias; lower manufacturing cost; reduced polymer layerresolution window issues; improved planarity in redistribution layers;and the like.

FIGS. 1 through 36 illustrate cross-sectional views of intermediatesteps during a process for forming a first package structure inaccordance with some embodiments. FIG. 1 illustrates a carrier substrate100 and a release layer 102 formed on the carrier substrate 100. A firstpackage region 600 and a second package region 602 for the formation ofa first package and a second package, respectively, are illustrated.

The carrier substrate 100 may be a glass carrier substrate, a ceramiccarrier substrate, or the like. The carrier substrate 100 may be awafer, such that multiple packages can be formed on the carriersubstrate 100 simultaneously. The release layer 102 may be formed of apolymer-based material, which may be removed along with the carriersubstrate 100 from the overlying structures that will be formed insubsequent steps. In some embodiments, the release layer 102 is anepoxy-based thermal-release material, which loses its adhesive propertywhen heated, such as a light-to-heat-conversion (LTHC) release coating.In other embodiments, the release layer 102 may be an ultra-violet (UV)glue, which loses its adhesive property when exposed to UV lights. Therelease layer 102 may be dispensed as a liquid and cured, may be alaminate film laminated onto the carrier substrate 100, or may be thelike. The top surface of the release layer 102 may be leveled and mayhave a high degree of coplanarity.

In FIG. 2, a dielectric layer 104 and a metallization pattern 106 areformed. As illustrated in FIG. 2, a dielectric layer 104 is formed onthe release layer 102. The bottom surface of the dielectric layer 104may be in contact with the top surface of the release layer 102. In someembodiments, the dielectric layer 104 is formed of a polymer, such aspolybenzoxazole (PBO), polyimide, benzocyclobutene (BCB), or the like.In other embodiments, the dielectric layer 104 is formed of a nitridesuch as silicon nitride; an oxide such as silicon oxide, phosphosilicateglass (PSG), borosilicate glass (BSG), boron-doped phosphosilicate glass(BPSG), or the like. The dielectric layer 104 may be formed by anyacceptable deposition process, such as spin coating, chemical vapordeposition (CVD), laminating, the like, or a combination thereof.

The metallization pattern 106 is formed on the dielectric layer 104. Asan example to form metallization pattern 106, a seed layer (not shown)is formed over the dielectric layer 104. In some embodiments, the seedlayer is a metal layer, which may be a single layer or a composite layercomprising a plurality of sub-layers formed of different materials. Forexample, the seed layer may comprise titanium, copper, molybdenum,tungsten, titanium nitride, titanium tungsten, combinations thereof, orthe like. In some embodiments, the seed layer comprises a titanium layerand a copper layer over the titanium layer. The seed layer may be formedusing, for example, PVD or the like. A photo resist is then formed andpatterned on the seed layer. The photo resist may be formed by spincoating or the like and may be exposed to light for patterning. Thepattern of the photo resist corresponds to the metallization pattern106. The patterning forms openings through the photo resist to exposethe seed layer. A conductive material is formed in the openings of thephoto resist and on the exposed portions of the seed layer. Theconductive material may be formed by plating, such as electroplating orelectroless plating, or the like. The conductive material may comprise ametal, like copper, titanium, tungsten, aluminum, or the like. Then, thephoto resist and portions of the seed layer on which the conductivematerial is not formed are removed. The photo resist may be removed byan acceptable ashing or stripping process, such as using an oxygenplasma or the like. Once the photo resist is removed, exposed portionsof the seed layer are removed, such as by using an acceptable etchingprocess, such as by wet or dry etching. The remaining portions of theseed layer and conductive material form the metallization pattern 106.

The dielectric layer 104 and the metallization patterns 106 may bereferred to as a back-side redistribution structure no. As illustrated,the back-side redistribution structure no includes the one dielectriclayer 104 one metallization pattern 106. In other embodiments, theback-side redistribution structure no can include any number ofdielectric layers, metallization patterns, and vias.

For example, in an embodiment, an additional dielectric layer (notshown) is optionally formed on the metallization pattern 106 and thedielectric layer 104. In some embodiments, the additional dielectriclayer is formed of a polymer, which may be a photo-sensitive materialsuch as PBO, polyimide, BCB, or the like, that may be patterned using alithography mask. In other embodiments, the additional dielectric layeris formed of a nitride such as silicon nitride; an oxide such as siliconoxide, PSG, BSG, BPSG; or the like. The additional dielectric layer maybe formed by spin coating, lamination, CVD, the like, or a combinationthereof. The additional dielectric layer is then patterned to formopenings to expose portions of the metallization pattern 106. Thepatterning may be by an acceptable process, such as by exposing thedielectric layer to light when the dielectric layer is a photo-sensitivematerial or by etching using, for example, an anisotropic etching.Subsequently formed conductive features may be electrically connected tothe metallization pattern 106 through conductive vias formed in theopenings of the additional dielectric layer.

One or more additional metallization patterns and dielectric layers maybe formed in the back-side redistribution structure no by repeating theprocesses for forming metallization patterns 106 and the optionaladditional dielectric layer (not shown). Vias may be formed during theformation of a metallization pattern by forming the seed layer andconductive material of the metallization pattern in the opening of theunderlying dielectric layer. Alternatively, the vias may be formed usingan embodiment via formation process as described below with respect toFIGS. 9 through 32. The vias may therefore interconnect and electricallycouple the various metallization patterns.

Further in FIG. 3, through vias 112 are formed. As an example to formthe through vias 112, a seed layer is formed over the back-sideredistribution structure 110, e.g., the dielectric layer 104 and themetallization pattern 106. In some embodiments, the seed layer is ametal layer, which may be a single layer or a composite layer comprisinga plurality of sub-layers formed of different materials. For example,the seed layer may comprise titanium, copper, molybdenum, tungsten,titanium nitride, titanium tungsten, combinations thereof, or the like.In some embodiments, the seed layer comprises a titanium layer and acopper layer over the titanium layer. The seed layer may be formedusing, for example, PVD or the like. A photo resist is formed andpatterned on the seed layer. The photo resist may be formed by spincoating or the like and may be exposed to light for patterning. Thepattern of the photo resist corresponds to the through vias 112. Thepatterning forms openings through the photo resist to expose the seedlayer. A conductive material is formed in the openings of the photoresist and on the exposed portions of the seed layer. The conductivematerial may be formed by plating, such as electroplating or electrolessplating, or the like. The conductive material may comprise a metal, likecopper, titanium, tungsten, aluminum, or the like. The photo resist andportions of the seed layer on which the conductive material is notformed are removed. The photo resist may be removed by an acceptableashing or stripping process, such as using an oxygen plasma or the like.Once the photo resist is removed, exposed portions of the seed layer areremoved, such as by using an acceptable etching process, such as by wetor dry etching. The remaining portions of the seed layer and conductivematerial form through vias 112. In other embodiments, the seed layer isomitted, and the metallization pattern 106 is used as a seed layer forforming the through vias 112.

In FIG. 4, integrated circuit dies 114 are adhered to the back-sideredistribution structure no by an adhesive 116. For example, theadhesive 116 may be adhered to a top surface of the metallizationpattern 106, and the adhesive 116 may further extend along sidewalls ofthe metallization patter 106. In other embodiments, such as when anadditional dielectric layer (not shown) is optionally formed over themetallization pattern 106, the adhesive 116 may be adhered to a topsurface of the optional additional dielectric layer.

As illustrated in FIG. 4, two integrated circuit dies 114 are adhered ineach of the first package region 600 and the second package region 602,and in other embodiments, more or less integrated circuit dies 114 maybe adhered in each region. For example, in an embodiment, only oneintegrated circuit die 114 may be adhered in each region. The integratedcircuit dies 114 may be logic dies (e.g., central processing unit,microcontroller, etc.), memory dies (e.g., dynamic random access memory(DRAM) die, static random access memory (SRAM) die, etc.), powermanagement dies (e.g., power management integrated circuit (PMIC) die),radio frequency (RF) dies, sensor dies, micro-electro-mechanical-system(MEMS) dies, signal processing dies (e.g., digital signal processing(DSP) die), front-end dies (e.g., analog front-end (AFE) dies), thelike, or a combination thereof. Also, in some embodiments, theintegrated circuit dies 114 may be different sizes (e.g., differentheights and/or surface areas), and in other embodiments, the integratedcircuit dies 114 may be the same size (e.g., same heights and/or surfaceareas).

Before being adhered to the dielectric layer 108, the integrated circuitdies 114 may be processed according to applicable manufacturingprocesses to form integrated circuits in the integrated circuit dies114. For example, the integrated circuit dies 114 each include asemiconductor substrate 118, such as silicon, doped or undoped, or anactive layer of a semiconductor-on-insulator (SOI) substrate. Thesemiconductor substrate may include other semiconductor material, suchas germanium; a compound semiconductor including silicon carbide,gallium arsenic, gallium phosphide, indium phosphide, indium arsenide,and/or indium antimonide; an alloy semiconductor including SiGe, GaAsP,AlInAs, AlGaAs, GalnAs, GaInP, and/or GaInAsP; or combinations thereof.Other substrates, such as multi-layered or gradient substrates, may alsobe used. Devices, such as transistors, diodes, capacitors, resistors,etc., may be formed in and/or on the semiconductor substrate 118 and maybe interconnected by interconnect structures 120 formed by, for example,metallization patterns in one or more dielectric layers on thesemiconductor substrate 118 to form an integrated circuit.

The integrated circuit dies 114 further comprise pads 122, such asaluminum pads, to which external connections are made. The pads 122 areon what may be referred to as respective active sides of the integratedcircuit dies 114. Passivation films 124 are on the integrated circuitdies 114 and on portions of the pads 122. Openings are through thepassivation films 124 to the pads 122. Die connectors 126, such asconductive pillars (for example, comprising a metal such as copper), arein the openings through passivation films 124 and are mechanically andelectrically coupled to the respective pads 122. The die connectors 126may be formed by, for example, plating, or the like. The die connectors126 electrically couple the respective integrated circuits of theintegrate circuit dies 114.

A dielectric material 128 is on the active sides of the integratedcircuit dies 114, such as on the passivation films 124 and the dieconnectors 126. The dielectric material 128 laterally encapsulates thedie connectors 126, and the dielectric material 128 is laterallycoterminous with the respective integrated circuit dies 114. Thedielectric material 128 may be a polymer such as PBO, polyimide, BCB, orthe like; a nitride such as silicon nitride or the like; an oxide suchas silicon oxide, PSG, BSG, BPSG, or the like; the like, or acombination thereof, and may be formed, for example, by spin coating,lamination, CVD, or the like.

Adhesive 116 is on back-sides of the integrated circuit dies 114 andadheres the integrated circuit dies 114 to the back-side redistributionstructure 110, such as the metallization pattern 106 in theillustration. The adhesive 116 may be any suitable adhesive, epoxy, dieattach film (DAF), or the like. The adhesive 116 may be applied to aback-side of the integrated circuit dies 114, such as to a back-side ofthe respective semiconductor wafer or may be applied over the surface ofthe carrier substrate 100. The integrated circuit dies 114 may besingulated, such as by sawing or dicing, and adhered to the dielectriclayer 104 by the adhesive 116 using, for example, a pick-and-place tool.

In FIG. 5, an encapsulant 130 is formed on the various components. Theencapsulant 130 may be a molding compound, epoxy, or the like, and maybe applied by compression molding, transfer molding, or the like. Aftercuring, the encapsulant 130 can undergo a grinding process to expose thethrough vias 112 and die connectors 126. Top surfaces of the throughvias 112, die connectors 126, and encapsulant 130 are coplanar after thegrinding process. In some embodiments, the grinding may be omitted, forexample, if through vias 112 and die connectors 126 are already exposed.

In FIGS. 6 through 8, a front-side redistribution structure 144 isformed. As will be illustrated in FIG. 8, the front-side redistributionstructure 144 includes metallization patterns 132, 136, 140, and 141 anddielectric layers 134, 138, and 142. Referring first to FIG. 6, themetallization pattern 132 and the dielectric layer 134 is formed on theencapsulant 130, the through vias 112, and the die connectors 126. Themetallization pattern 132 includes conductive lines 132A and conductivevias 132B. The conductive lines 132A may be formed directly on theencapsulant 130, the through vias 112, and the die connectors 126. Forexample, there may be no intermediary interconnect features (e.g., otherconductive lines and/or vias) between the conductive lines 132A and thethrough vias 112/die connectors 126. The conductive lines 132A mayprovide electrical routing to route electrical signals (e.g., to/fromthe through vias 112 and/or the die connectors 126) to a differentphysical location depending on a desired layout design. The conductivevias 132B are formed over the conductive lines 132A, and the conductivevias 132B allow electrical signals to pass to upper layers, e.g., uppermetallization patterns 136, 140, and 141 (see FIGS. 7 and 8). Thedielectric layer 134 is formed around the metallization pattern 132. Insome embodiments, the dielectric layer 134 is formed of a polymer, whichmay be a photo-sensitive material such as PBO, polyimide, BCB, or thelike, that may be patterned using a lithography mask. In otherembodiments, the dielectric layer 134 is formed of a nitride such assilicon nitride; an oxide such as silicon oxide, PSG, BSG, BPSG; or thelike. The metallization pattern 132 and the dielectric layer 134 may beformed using any suitable formation process, such as the processdescribed in the embodiments of FIGS. 9 through 17, FIGS. 18 through 20,FIGS. 21 through 23, and/or FIGS. 24 through 32.

Referring to FIG. 7, a metallization pattern 136 and a dielectric layer138 are formed over the metallization pattern 132 and the dielectriclayer 134. The metallization pattern 136 includes conductive lines 136Aand conductive vias 136B. The conductive lines 136A may be formeddirectly on the metallization pattern 132 and the dielectric layer 134.For example, there may be no intermediary interconnect features (e.g.,other conductive lines and/or vias) between the conductive lines 136Aand the conductive vias 132B of the metallization pattern 132. Theconductive lines 136A may provide electrical routing to route electricalsignals (e.g., to/from conductive vias 132B) to a different physicallocation depending on a desired layout design. The conductive vias 136Bare formed over the conductive lines 136A, and the conductive vias 136Ballow electrical signals to pass to upper layers, e.g., uppermetallization patterns 140 and 141 (see FIG. 8). The dielectric layer138 is formed around the metallization pattern 136. In some embodiments,the dielectric layer 138 is formed of a polymer, which may be aphoto-sensitive material such as PBO, polyimide, BCB, or the like, thatmay be patterned using a lithography mask. In other embodiments, thedielectric layer 138 is formed of a nitride such as silicon nitride; anoxide such as silicon oxide, PSG, BSG, BPSG; or the like. Themetallization pattern 136 and the dielectric layer 138 may be formedusing any suitable formation process, such as the process described inthe embodiments of FIG. 9 through 17, FIGS. 18 through 20, FIGS. 21through 23, and/or FIGS. 24 through 32.

Referring to FIG. 8, a metallization pattern 140, a metallizationpattern 141, and a dielectric layer 142 are formed over themetallization pattern 136 and the dielectric 138. The metallizationpattern 140 includes conductive lines, which may be formed directly onthe metallization pattern 136 and the dielectric layer 138. For example,there may be no intermediary interconnect features (e.g., otherconductive lines and/or vias) between the conductive lines of themetallization pattern 140 and the conductive vias 136B of themetallization pattern 136. The conductive lines of the metallizationpattern 140 may provide electrical routing to route electrical signals(e.g., to/from conductive vias 136B) to a different physical locationdepending on a desired layout design.

As also illustrated by FIG. 8, metallization pattern 141 are formed onthe metallization pattern 140. The metallization pattern 141 are used tocouple to conductive connectors 148 and/or surface mount devices (SMDs)146 (see FIG. 33) and may be referred to as under bump metallurgies(UBMs) 141. In the illustrated embodiment, the UBMs 141 are formedthrough openings in the dielectric layer 142 to the metallizationpattern 140.

The dielectric layer 142 is formed around the metallization pattern 140and the UBMs 141. In some embodiments, the dielectric layer 142 isformed of a polymer, which may be a photo-sensitive material such asPBO, polyimide, BCB, or the like, that may be patterned using alithography mask. In other embodiments, the dielectric layer 142 isformed of a nitride such as silicon nitride; an oxide such as siliconoxide, PSG, BSG, BPSG; or the like. The metallization pattern 140, UBMs141, and the dielectric layer 142 may be formed using any suitableformation process, such as the process described in the embodiments ofFIGS. 9 through 17, FIGS. 18 through 20, FIGS. 21 through 23, and/orFIGS. 24 through 32.

FIGS. 9 through 17 illustrate various intermediary steps of forming ametallization pattern (e.g., the metallization patterns 132, 136, 140,and/or 141) in a dielectric layer (e.g., dielectric layer 134, 138,and/142). Referring to FIG. 9, a substrate 150 is illustrated. Substrate150 may be any layer immediately underlying a subsequently formedmetallization pattern/dielectric layer. For example, the substrate 150may include a metallization pattern in a dielectric layer.Alternatively, the substrate 150 may include die connectors to anintegrated circuit die, an encapsulant, and through vias. In yet otherembodiments, the substrate 150 may include any suitable combination ofmaterial(s) depending on package design.

As also illustrated by FIG. 9, a seed layer 152 is formed over thesubstrate 150. In some embodiments, the seed layer is a metal layer,which may be a single layer or a composite layer comprising a pluralityof sub-layers formed of different materials. For example, the seed layer152 may comprise titanium, copper, molybdenum, tungsten, titaniumnitride, titanium tungsten, combinations thereof, or the like. In someembodiments, the seed layer comprises a titanium layer 152A and a copperlayer 152B over the titanium layer 152A. The seed layer 152 may beformed using, for example, PVD or the like. In some embodiments a topsurface of substrate 150 (e.g., a surface on which seed layer 152 isformed) is substantially coplanar. When seed layer 152 is deposited onthe top surface of substrate 150, a top surface of seed layer 152 mayadopt a profile of the top surface of substrate 150. For example, seedlayer 152 may have a top surface that is also substantially coplanar.

In FIGS. 10 and 11, a first mask 154 is formed and patterned on the seedlayer 152. In some embodiments, the first mask is a photo resist and maybe referred to as first photo resist 154 hereinafter. The first photoresist 154 may be formed by spin coating as a blanket layer (see FIG.10). After the first photo resist 154 is deposited, the first photoresist 154 may be exposed, for example to UV light or another radiationsource through a patterned photomask. The first photo resist 154 maythen be developed and either exposed or unexposed portions of the firstphoto resist 154 is removed depending on whether a positive or negativeresist is used. The resulting patterned first photo resist 156 isillustrated in FIG. 11, which illustrates the patterned first photoresist 156 having openings 157 extending therethrough. The pattern ofthe patterned first photo resist 156 corresponds to conductive lines 158of the metallization pattern (see FIG. 12). The openings 157 extendthrough the patterned first photo resist 156 and exposes the seed layer152.

Subsequently, in FIG. 12, a conductive material (a portion of conductivelines 158) is formed in the openings 157 of the patterned first photoresist 156 (see FIG. 11) and on the exposed portions of the seed layer152. The conductive lines 158 may be formed by plating, such aselectroplating or electroless plating, or the like. The conductive lines158 may comprise a metal, like copper, titanium, tungsten, aluminum, orthe like. Then, as also illustrated by FIG. 12, the patterned firstphoto resist 156 is removed by an acceptable ashing or strippingprocess, such as using an oxygen plasma or the like. The conductivelines 158 may correspond to the conductive lines 132A, the conductivelines 136A, and/or the metallization pattern 140 of FIGS. 6 through 8.For example, the conductive lines 132A, the conductive lines 136A,and/or the metallization pattern 140 may be formed using a processsimilar to the conductive lines 158 as described herein.

Once the patterned first photo resist 156 is removed, a second mask 160is deposited over the seed layer 152 and the conductive lines 158. Insome embodiments, the second mask is a photo resist and may be referredto as second photo resist 160 hereinafter. The second photo resist 160may be formed by spin coating as a blanket layer (see FIG. 13). Afterthe second photo resist 160 is deposited, the second photo resist 160may be exposed, for example to UV light or another radiation sourcethrough a patterned photomask. The second photo resist 160 may then bedeveloped and either exposed or unexposed portions of the second photoresist 160 is removed depending on whether a positive or negative resistis used. The resulting patterned second photo resist 162 having openings161 extending therethrough is illustrated in FIG. 15. The pattern of thepatterned second photo resist 162 corresponds to the conductive vias 164of the metallization pattern (see FIG. 15). The openings 161 extendthrough the patterned second photo resist 162 and exposes the conductivelines 158.

In some embodiments, a material of the patterned second photo resist 162and/or the patterned first photo resist 156 may support relatively highresolution lithography patterning, which allows for the formation ofrelatively fine-pitched openings. For example, in an embodiment, a widthof each opening 161 may be less than about 1 μm. By employing a highresolution photo resist material, subsequently formed features in theopenings 161 (e.g., conductive vias 164, see FIG. 15) may have smallerdimensions. Thus, a density of metallization features can beadvantageously increased. In some embodiments, the patterned first photoresist 156 and/or the patterned second photo resist 162 may compriseamino compounds such as melamine resins, urea resins, guanamine resins,glycoluril-formaldehyde resins, succinamide-formaldehyde resins,ethylene urea-formaldehyde resins, and combinations thereof.

Subsequently, in FIG. 15, a conductive material (e.g., conductive vias164) is formed in the openings 161 (see FIG. 14) and on the exposedportions of the conductive lines 158. Forming the conductive vias 164uses the conductive lines 158 as a seed layer without depositingseparate seed layer(s) for the conductive vias 164, which allows theconductive vias 164 to be formed at a relatively low manufacturing cost.The conductive vias 164 may be formed by plating, such as electroplatingor electroless plating, or the like. The conductive vias 164 maycomprise a metal, like copper, titanium, tungsten, aluminum, or thelike. Then, as also illustrated by FIG. 15, the patterned second photoresist 162 is removed by an acceptable ashing or stripping process, suchas using an oxygen plasma or the like. The conductive vias 164 maycorrespond to the conductive vias 132B, the conductive vias 136B, and/orthe UBMs 141 of FIGS. 6 through 8. For example, the conductive vias136B, the conductive vias 132B, and/or the UBMs 141 may be formed usinga process similar to the conductive vias 164 as described herein.

After the patterned second photo resist 162 is removed, exposed portionsof the seed layer 152 are removed, such as by using an acceptableetching process, such as by wet or dry etching. The remaining portionsof the seed layer 152 and conductive material form a metallizationpattern comprising the conductive lines 158 and the conductive vias 164.

In FIGS. 16 and 17, a dielectric layer 166 is deposited around theconductive lines 158 and the conductive vias 164. In some embodiments,the dielectric layer 166 is formed of a polymer, which may be aphoto-sensitive material such as PBO, polyimide, BCB, or the like, thatmay be patterned using a lithography mask. In other embodiments, thedielectric layer 166 is formed of a nitride such as silicon nitride; anoxide such as silicon oxide, PSG, BSG, BPSG; or the like. The dielectriclayer 166 may be formed by spin coating, lamination, CVD, the like, or acombination thereof. In embodiments where the dielectric layer 166comprises a photosensitive material, the dielectric layer 166 maycomprise a different type of material than the first photo resist 154(see FIG. 10) and/or the second photo resist 160 (see FIG. 13). Forexample, the first photo resist 154 and/or the second photo resist 160may support a higher resolution lithography process than the dielectriclayer 166.

The dielectric layer 166 may be initially formed to completely cover topsurfaces of the conductive lines 158 and the conductive vias 164 asillustrated by FIG. 16. Subsequently, a CMP or other suitableplanarization process may be applied to the dielectric layer 166 tolevel a top surface of the dielectric layer 166 and to expose theconductive vias 164. The dielectric layer 166 may correspond to thedielectric layer 134, the dielectric layer 138, and/or the dielectriclayer 142 of FIGS. 6 through 8. For example, the dielectric layer 134,the dielectric layer 138, and/or the dielectric layer 142 may be formedusing a process similar to the dielectric layer 166. Subsequently,additional features may be formed over the dielectric layer 166 and theconductive vias 164. For example, additional metallization patterns indielectric layers may be formed over the dielectric layer 166 byrepeating the process described in FIGS. 9 through 17.

In the process of FIGS. 9 through 17, the openings 161 in the patternedsecond photo resist 162 (see FIG. 14) are aligned with the conductivelines 158 so that the patterned second photo resist 162 only exposes atop surface of the conductive lines 158. In other embodiments, thepatterned second photo resist 162 exposes top surfaces of the conductivelines 158 as well as sidewalls of the conductive lines 158.

For example, FIGS. 18 to 20 illustrate various intermediary steps offorming a metallization pattern according to some embodiments. In FIG.18, a patterned second photo resist 162 is formed over the conductivelines 158. The various features of FIG. 18 may be similar to features in14 where like reference numerals indicate like elements formed usinglike processes, such as, those processes described in FIGS. 9 through14.

As illustrated by FIG. 18, openings 168 are formed in the patternedsecond photo resist 162. The openings 168 expose top surfaces as well assidewalls of the conductive lines 158, and a bottom surface of theopenings 168 may be defined by a material of the conductive lines 158 aswell as a material of the patterned second photo resist 162. In FIG. 18,the openings 168 extend only partially through the patterned secondphoto resist 162. For example, portions of the patterned second photoresist 162 are disposed between bottom surfaces of the openings 168 anda top surface of the seed layer 152. A depth of the openings 168 may becontrolled, for example, by controlling exposure conditions (e.g.,focus, energy, or the like) during the photolithography process.

Subsequently, in FIG. 19, a conductive material (conductive vias 170) isformed in the openings 168 of the patterned second photo resist 162 (seeFIG. 18) and on the exposed portions of the conductive lines 158.Forming the conductive vias 170 uses the conductive lines 158 as a seedlayer without depositing separate seed layer(s) for the conductive vias170, which allows the conductive vias 170 to be formed at a relativelylow manufacturing cost. The conductive vias 170 may be formed byplating, such as electroplating or electroless plating, or the like. Theconductive vias 170 may comprise a metal, like copper, titanium,tungsten, aluminum, or the like. Then, as also illustrated by FIG. 19,the patterned second photo resist 162 is removed by an acceptable ashingor stripping process, such as using an oxygen plasma or the like. Thepatterned second photo resist 162 be removed by an acceptable ashing orstripping process, such as using an oxygen plasma or the like. Theconductive vias 170 may correspond to the conductive vias 132B, theconductive vias 136B, and/or the UBMs 141 of FIGS. 6 through 8. Forexample, the conductive vias 132B, the conductive vias 136B, and/or theUBMs 141 may be formed using a process similar to the conductive vias170 as described herein.

Subsequently, the patterned second photo resist 162 is removed by anacceptable ashing or stripping process, such as using an oxygen plasmaor the like. After the patterned second photo resist 162 is removed,exposed portions of the seed layer 152 are removed, such as by using anacceptable etching process, such as by wet or dry etching. The remainingportions of the seed layer and conductive material form a metallizationpattern comprising the conductive lines 158 and the conductive vias 170.

Due to the position of the openings 168 (see FIG. 18), the position ofthe conductive vias 170 may likewise be different than the conductivevias 164 (see FIG. 17). For example, the conductive vias 170 may onlypartially overlap the underlying conductive lines 158, and portions ofthe conductive vias 170 may overhang and extend further than theunderlying conductive line 158.

Subsequently, as illustrated by FIG. 20, the dielectric layer 166 isdeposited around the conductive lines 158 and the conductive vias 170.The dielectric layer 166 may be deposited to cover the conductive lines158 and the conductive vias 170. After deposition, a CMP or otherplanarization process may be applied to the dielectric layer 166 toexpose the conductive vias 170 and improve a planarity of a top surfaceof the dielectric layer 166. A portion of the dielectric layer 166 maybe disposed between a bottom surface of the conductive vias 170 and alayer immediately underlying the dielectric layer 166 (e.g., thesubstrate 150). Subsequently, additional features may be formed over thedielectric layer 166 and the conductive vias 170. For example,additional metallization patterns in dielectric layers may be formedover the dielectric layer 166 by repeating the process described inFIGS. 18 through 20.

FIGS. 21 to 23 illustrate various intermediary steps of forming ametallization pattern according to some other embodiments. In FIG. 21, apatterned second photo resist 162 is formed over the conductive lines158. The various features of FIG. 21 may be similar to features in 14where like reference numerals indicate like elements formed using likeprocesses, such as, those processes described in FIGS. 9 through 14.

As illustrated by FIG. 21, openings 174 are formed in the patternedsecond photo resist 162. The openings 174 expose top surfaces as well assidewalls of the conductive lines 158, and a bottom surface of theopenings 168 may be defined by a material of the conductive lines 158 aswell as a material of the seed layer 152. Unlike the openings 168 (seeFIG. 18), the openings 174 extend completely through the patternedsecond photo resist 162 to expose the seed layer 152. A depth of theopenings 174 may be controlled, for example, by controlling exposureconditions (e.g., focus, energy, or the like) during thephotolithography process.

Subsequently, in FIG. 22, a conductive material (conductive vias 176) isformed in the openings 174 of the patterned second photo resist 162 (seeFIG. 21) and on the exposed portions of the conductive lines 158 and theseed layer 152. Forming the conductive vias 176 uses the conductivelines 158 and the seed layer 152 as seed layers without depositingseparate seed layer(s) for the conductive vias 176. This allows theconductive vias 176 to be formed at a relatively low manufacturing cost.The conductive vias 176 may be formed by plating, such as electroplatingor electroless plating, or the like. The conductive vias 176 maycomprise a metal, like copper, titanium, tungsten, aluminum, or thelike. Then, as also illustrated by FIG. 22, the patterned second photoresist 162 is removed by an acceptable ashing or stripping process, suchas using an oxygen plasma or the like. The patterned second photo resist162 be removed by an acceptable ashing or stripping process, such asusing an oxygen plasma or the like. The conductive vias 176 maycorrespond to the conductive vias 132B, the conductive vias 136B and/orthe UBMs 141 of FIGS. 6 through 8. For example, the conductive vias132B, the conductive vias 136B, and/or the UBMs 141 may be formed usinga process similar to the conductive vias 176 as described herein.

Subsequently, the patterned second photo resist 162 is removed by anacceptable ashing or stripping process, such as using an oxygen plasmaor the like. After the patterned second photo resist 162 is removed,exposed portions of the seed layer 152 are removed, such as by using anacceptable etching process, such as by wet or dry etching. The remainingportions of the seed layer and conductive material form a metallizationpattern comprising the conductive lines 158 and the conductive vias 176.

Due to the position of the openings 174 (see FIG. 21), the position ofthe conductive vias 176 may likewise be different than the conductivevias 164 (see FIG. 17) or the conductive vias 170 (see FIG. 19). Forexample, the conductive vias 176 may be disposed at edges of theconductive lines 158, and a line extending along a sidewall of aconductive via 176 may also extend along a sidewall of a conductive line158.

Subsequently, as illustrated by FIG. 23, the dielectric layer 166 isdeposited around the conductive lines 158 and the conductive vias 176.The dielectric layer 166 may be deposited to cover the conductive lines158 and the conductive vias 176. After deposition, a CMP or otherplanarization process may be applied to the dielectric layer 166 toexpose the conductive vias 176 and improve a planarity of a top surfaceof the dielectric layer 166. Subsequently, additional features may beformed over the dielectric layer 166 and the conductive vias 176. Forexample, additional metallization patterns in dielectric layers may beformed over the dielectric layer 166 by repeating the process describedin FIGS. 21 through 23.

FIGS. 24 through 32 illustrate various intermediary steps of forming ametallization pattern (e.g., the metallization patterns 132, 136, 140,and/or 141) in a dielectric layer (e.g., dielectric layer 134, 138,and/or 142) according to some other embodiments. Referring to FIG. 24, asubstrate 150 is illustrated. Substrate 150 may be any layer immediatelyunderlying a subsequently formed metallization pattern/dielectric layer.For example, the substrate 150 may include a metallization pattern in adielectric layer. Alternatively, the substrate 150 may includeconnectors to an integrated circuit die, an encapsulant, and throughvias. In yet other embodiments, the substrate 150 may include anysuitable material(s).

As also illustrated by FIG. 24, a seed layer 180 is formed over thesubstrate 150. In some embodiments, the seed layer is a metal layer,which may be a single layer or a composite layer comprising a pluralityof sub-layers formed of different materials. For example, the seed layer180 may comprise titanium, copper, molybdenum, tungsten, titaniumnitride, titanium tungsten, combinations thereof, or the like. In someembodiments, the seed layer comprises a titanium layer 180A and a copperlayer 180B over the titanium layer 180A. The seed layer 180 may beformed using, for example, PVD or the like.

In FIG. 25, a patterned first photo resist 182 is formed on the seedlayer 180. The patterned first photo resist 182 may be formed by spincoating as a blanket layer a photo resist material. In some embodiments,the patterned first photo resist 182 may comprise amino compounds suchas melamine resins, urea resins, guanamine resins,glycoluril-formaldehyde resins, succinamide-formaldehyde resins,ethylene urea-formaldehyde resins, and combinations thereof. After thephoto resist material is deposited, the photo resist material may beexposed, for example to UV light or another radiation source through apatterned photomask. The photo resist material may then be developed andexposed or unexposed portions of the photo resist material is removeddepending on whether a positive or negative resist is used. Theresulting patterned first photo resist 182 is illustrated in FIG. 25,which illustrates the patterned first photo resist 182 having openings184 extending therethrough. The pattern of the patterned first photoresist 182 corresponds to conductive vias 186 of the metallizationpattern (see FIG. 26). The openings 184 extend through the patternedfirst photo resist 182 and exposes the seed layer 180.

Subsequently, in FIG. 26, a conductive material (conductive vias 186) isformed in the openings 184 of the patterned first photo resist 182 (seeFIG. 25) and on the exposed portions of the seed layer 180. Theconductive vias 186 may be formed by plating, such as electroplating orelectroless plating, or the like. The conductive vias 186 may comprise ametal, like copper, titanium, tungsten, aluminum, or the like. Then, asalso illustrated by FIG. 26, the patterned first photo resist 182 isremoved by an acceptable ashing or stripping process, such as using anoxygen plasma or the like. The conductive vias 186 may correspond to theconductive vias 132B, the conductive vias 136B, and/or the UBMs 141 ofFIGS. 6 through 8. For example, the conductive vias 132B, the conductivevias 136B, and/or the UBMs 141 may be formed using a process similar tothe conductive vias 186 as described herein.

Once the patterned first photo resist 182 is removed, a dielectric layer188 is deposited around the conductive vias 186 as illustrated by FIG.27. In some embodiments, the dielectric layer 188 is formed of apolymer, which may be a photo-sensitive material such as PBO, polyimide,BCB, or the like, that may be patterned using a lithography mask. Inother embodiments, the dielectric layer 188 is formed of a nitride suchas silicon nitride; an oxide such as silicon oxide, PSG, BSG, BPSG; orthe like. In embodiments where the dielectric layer 188 comprises aphotosensitive material, the dielectric layer 166 may comprise adifferent type of material than the patterned first photo resist 182(see FIG. 25). For example, the patterned first photo resist 182 maysupport a higher resolution lithography process than the dielectriclayer 166.

The dielectric layer 188 may be formed by spin coating, lamination, CVD,the like, or a combination thereof. The dielectric layer 188 may beinitially formed to completely cover top surfaces of the conductive vias182 as illustrated by FIG. 27. Subsequently, a CMP or other suitableplanarization process may be applied to the dielectric layer 188 tolevel a top surface of the dielectric layer 188 and to expose theconductive vias 186 as illustrated by FIG. 28.

Subsequently, in FIGS. 29 through 31, conductive lines 158 are formedover the dielectric layer 188 and the conductive vias 186. Theconductive lines 158 may be electrically connected to the underlyingconductive vias 186. Forming the conductive lines 158 may includesimilar processes as those described in FIGS. 9 through 12 where likereference numerals indicate like elements. After the conductive lines158 are formed, exposed portions of the seed layer 152 are removed, suchas by using an acceptable etching process, such as by wet or dryetching. The remaining portions of the seed layer and conductivematerial form a metallization pattern comprising the conductive lines158.

Next, as illustrated by FIG. 32, the dielectric layer 166 is depositedaround the conductive lines 158. The dielectric layer 166 may bedeposited to cover the conductive lines 158. After deposition, a CMP orother planarization process may be applied to the dielectric layer 166to expose the conductive lines 158 and improve a planarity of a topsurface of the dielectric layer 166. Subsequently, additional featuresmay be formed over the dielectric layer 166 and the conductive lines158. For example, additional metallization patterns in dielectric layersmay be formed over the dielectric layer 166 by repeating the processdescribed in FIGS. 24 through 32.

FIGS. 33 through 36 illustrate cross-sectional views of intermediatesteps during a process for further forming a first package and forattaching other package structures to the first package in accordancewith some embodiments. The processes of FIGS. 33 through 36 may beperformed after forming metallization patterns in front-sideredistribution structure 144 using the various embodiment processesdescribed herein.

Referring to FIG. 33, conductive connectors 166 are formed on the UBMs141. The conductive connectors 166 may be BGA connectors, solder balls,metal pillars, controlled collapse chip connection (C4) bumps, microbumps, electroless nickel-electroless palladium-immersion gold technique(ENEPIG) formed bumps, or the like. The conductive connectors 166 mayinclude a conductive material such as solder, copper, aluminum, gold,nickel, silver, palladium, tin, the like, or a combination thereof. Insome embodiments, the conductive connectors 166 are formed by initiallyforming a layer of solder through such commonly used methods such asevaporation, electroplating, printing solder transfer, ball placement,or the like. Once a layer of solder has been formed on the structure, areflow may be performed in order to shape the material into the desiredbump shapes. In another embodiment, the conductive connectors 166 aremetal pillars (such as a copper pillar) formed by a sputtering,printing, electro plating, electroless plating, CVD, or the like. Themetal pillars may be solder free and have substantially verticalsidewalls. In some embodiments, a metal cap layer (not shown) is formedon the top of the metal pillar connectors 166. The metal cap layer mayinclude nickel, tin, tin-lead, gold, silver, palladium, indium,nickel-palladium-gold, nickel-gold, the like, or a combination thereofand may be formed by a plating process.

As further illustrated by FIG. 33, surface mount device (SMDs) 146 mayalso be formed on the UBMs 141. SMDs 146 may include passive devicessuch as, capacitors, resistors, inductors, combinations thereof, or thelike. SMDs 146 may be electrically connected to the integrated circuitdies 114 through the metallization patterns in the redistributionstructure 144.

In FIG. 34, a carrier substrate de-bonding is performed to detach(de-bond) the carrier substrate 100 from the back-side redistributionstructure, e.g., dielectric layer 104. In accordance with someembodiments, the de-bonding includes projecting a light such as a laserlight or an UV light on the release layer 102 so that the release layer102 decomposes under the heat of the light and the carrier substrate 100can be removed. The structure is then flipped over and placed on a tape190.

As further illustrated in FIG. 34, openings are formed through thedielectric layer 104 to expose portions of the metallization pattern106. The openings may be formed, for example, using laser drilling,etching, or the like.

In FIG. 35, a singulation process is performed by sawing along scribeline regions e.g., between adjacent regions 600 and 602. The sawingsingulates the first package region 600 from the second package region602.

FIG. 35 illustrates a resulting, singulated package 200, which may befrom one of the first package region 600 or the second package region602. The package 200 may also be referred to as an integrated fan-out(InFO) package 200.

FIG. 36 illustrates a package structure 500 including the package 200(may be referred to as a first package 200), a second package 300, and asubstrate 400. The second package 300 includes a substrate 302 and oneor more stacked dies 308 (308A and 308B) coupled to the substrate 302.The substrate 302 may be made of a semiconductor material such assilicon, germanium, diamond, or the like. In some embodiments, compoundmaterials such as silicon germanium, silicon carbide, gallium arsenic,indium arsenide, indium phosphide, silicon germanium carbide, galliumarsenic phosphide, gallium indium phosphide, combinations of these, andthe like, may also be used. Additionally, the substrate 302 may be asilicon-on-insulator (SOI) substrate. Generally, an SOI substrateincludes a layer of a semiconductor material such as epitaxial silicon,germanium, silicon germanium, SOI, silicon germanium on insulator(SGOI), or combinations thereof. The substrate 302 is, in onealternative embodiment, based on an insulating core such as a fiberglassreinforced resin core. One example core material is fiberglass resinsuch as FR4. Alternatives for the core material includebismaleimide-triazine (BT) resin, or alternatively, other printedcircuit board (PCB) materials or films. Build up films such as Ajinomotobuild-up film (ABF) or other laminates may be used for substrate 302.

The substrate 302 may include active and passive devices (not shown inFIG. 28). As one of ordinary skill in the art will recognize, a widevariety of devices such as transistors, capacitors, resistors,combinations of these, and the like may be used to generate thestructural and functional requirements of the design for thesemiconductor package 300. The devices may be formed using any suitablemethods.

The substrate 302 may also include metallization layers (not shown) andthrough vias 306. The metallization layers may be formed over the activeand passive devices and are designed to connect the various devices toform functional circuitry. The metallization layers may be formed ofalternating layers of dielectric (e.g., low-k dielectric material) andconductive material (e.g., copper) with vias interconnecting the layersof conductive material and may be formed through any suitable process(such as deposition, damascene, dual damascene, or the like). In someembodiments, the substrate 302 is substantially free of active andpassive devices.

The substrate 302 may have bond pads 303 on a first side the substrate302 to couple to the stacked dies 308, and bond pads 304 on a secondside of the substrate 302, the second side being opposite the first sideof the substrate 302, to couple to the conductive connectors 314. Insome embodiments, the bond pads 303 and 304 are formed by formingrecesses (not shown) into dielectric layers (not shown) on the first andsecond sides of the substrate 302. The recesses may be formed to allowthe bond pads 303 and 304 to be embedded into the dielectric layers. Inother embodiments, the recesses are omitted as the bond pads 303 and 304may be formed on the dielectric layer. In some embodiments, the bondpads 303 and 304 include a thin seed layer (not shown) made of copper,titanium, nickel, gold, palladium, the like, or a combination thereof.The conductive material of the bond pads 303 and 304 may be depositedover the thin seed layer. The conductive material may be formed by anelectro-chemical plating process, an electroless plating process, CVD,ALD, PVD, the like, or a combination thereof. In an embodiment, theconductive material of the bond pads 303 and 304 is copper, tungsten,aluminum, silver, gold, the like, or a combination thereof.

In an embodiment, the bond pads 303 and 304 are UBMs that include threelayers of conductive materials, such as a layer of titanium, a layer ofcopper, and a layer of nickel. However, one of ordinary skill in the artwill recognize that there are many suitable arrangements of materialsand layers, such as an arrangement of chrome/chrome-copperalloy/copper/gold, an arrangement of titanium/titanium tungsten/copper,or an arrangement of copper/nickel/gold, that are suitable for theformation of the UBMs 303 and 304. Any suitable materials or layers ofmaterial that may be used for the UBMs 303 and 304 are fully intended tobe included within the scope of the current application. In someembodiments, the through vias 306 extend through the substrate 302 andcouple at least one bond pad 303 to at least one bond pad 304.

In the illustrated embodiment, the stacked dies 308 are coupled to thesubstrate 302 by wire bonds 310, although other connections may be used,such as conductive bumps. In an embodiment, the stacked dies 308 arestacked memory dies. For example, the stacked memory dies 308 mayinclude low-power (LP) double data rate (DDR) memory modules, such asLPDDR1, LPDDR2, LPDDR3, LPDDR4, non-volatile memory, or the like memorymodules.

In some embodiments, the stacked dies 308 and the wire bonds 310 may beencapsulated by a molding material 312. The molding material 312 may bemolded on the stacked dies 308 and the wire bonds 310, for example,using compression molding. In some embodiments, the molding material 312is a molding compound, a polymer, an epoxy, silicon oxide fillermaterial, the like, or a combination thereof. A curing step may beperformed to cure the molding material 312, wherein the curing may be athermal curing, a UV curing, the like, or a combination thereof.

In some embodiments, the stacked dies 308 and the wire bonds 310 areburied in the molding material 312, and after the curing of the moldingmaterial 312, a planarization step, such as a grinding, is performed toremove excess portions of the molding material 312 and provide asubstantially planar surface for the second packages 300.

After the second packages 300 are formed, the packages 300 are bonded tothe first packages 200 by way of conductive connectors 314, the bondpads 304, and the metallization pattern 106. In some embodiments, thestacked memory dies 308 may be coupled to the integrated circuit dies114 through the wire bonds 310, the bond pads 303 and 304, through vias306, the conductive connectors 314, and the through vias 112.

The conductive connectors 314 may be similar to the conductiveconnectors 166 described above and the description is not repeatedherein, although the conductive connectors 314 and 166 need not be thesame. In some embodiments, before bonding the conductive connectors 314,the conductive connectors 314 are coated with a flux (not shown), suchas a no-clean flux. The conductive connectors 314 may be dipped in theflux or the flux may be jetted onto the conductive connectors 314. Inanother embodiment, the flux may be applied to the surfaces of themetallization patterns 106.

In some embodiments, the conductive connectors 314 may have an epoxyflux (not shown) formed thereon before they are reflowed with at leastsome of the epoxy portion of the epoxy flux remaining after the secondpackage 300 is attached to the first package 200. This remaining epoxyportion may act as an underfill to reduce stress and protect the jointsresulting from the reflowing the conductive connectors 314. In someembodiments, an underfill (not shown) may be formed between the secondpackage 300 and the first package 200 and surrounding the conductiveconnectors 314. The underfill may be formed by a capillary flow processafter the second package 300 is attached or may be formed by a suitabledeposition method before the second package 300 is attached.

The bonding between the second package 300 and the first package 200 maybe a solder bonding or a direct metal-to-metal (such as acopper-to-copper or tin-to-tin) bonding. In an embodiment, the secondpackage 300 is bonded to the first package 200 by a reflow process.During this reflow process, the conductive connectors 314 are in contactwith the bond pads 304 and the metallization patterns 106 to physicallyand electrically couple the second package 300 to the first package 200.After the bonding process, an IMC (not shown) may form at the interfaceof the metallization patterns 106 and the conductive connectors 314 andalso at the interface between the conductive connectors 314 and the bondpads 304 (not shown).

The semiconductor package 500 includes the packages 200 and 300 beingmounted to a substrate 400. The substrate 400 may be referred to apackage substrate 400. The package 200 is mounted to the packagesubstrate 400 using the conductive connectors 166.

The package substrate 400 may be made of a semiconductor material suchas silicon, germanium, diamond, or the like. Alternatively, compoundmaterials such as silicon germanium, silicon carbide, gallium arsenic,indium arsenide, indium phosphide, silicon germanium carbide, galliumarsenic phosphide, gallium indium phosphide, combinations of these, andthe like, may also be used. Additionally, the package substrate 400 maybe a SOI substrate. Generally, an SOI substrate includes a layer of asemiconductor material such as epitaxial silicon, germanium, silicongermanium, SOI, SGOI, or combinations thereof. The package substrate 400is, in one alternative embodiment, based on an insulating core such as afiberglass reinforced resin core. One example core material isfiberglass resin such as FR4. Alternatives for the core material includebismaleimide-triazine BT resin, or alternatively, other PCB materials orfilms. Build up films such as ABF or other laminates may be used forpackage substrate 400.

The package substrate 400 may include active and passive devices (notshown in FIG. 36). As one of ordinary skill in the art will recognize, awide variety of devices such as transistors, capacitors, resistors,combinations of these, and the like may be used to generate thestructural and functional requirements of the design for thesemiconductor package 500. The devices may be formed using any suitablemethods.

The package substrate 400 may also include metallization layers and vias(not shown) and bond pads 402 over the metallization layers and vias.The metallization layers may be formed over the active and passivedevices and are designed to connect the various devices to formfunctional circuitry. The metallization layers may be formed ofalternating layers of dielectric (e.g., low-k dielectric material) andconductive material (e.g., copper) with vias interconnecting the layersof conductive material and may be formed through any suitable process(such as deposition, damascene, dual damascene, or the like). In someembodiments, the package substrate 400 is substantially free of activeand passive devices.

In some embodiments, the conductive connectors 166 can be reflowed toattach the package 200 to the bond pads 402. The conductive connectors166 electrically and/or physically couple the substrate 400, includingmetallization layers in the substrate 400, to the first package 200.

The conductive connectors 166 may have an epoxy flux (not shown) formedthereon before they are reflowed with at least some of the epoxy portionof the epoxy flux remaining after the package 200 is attached to thesubstrate 400. This remaining epoxy portion may act as an underfill toreduce stress and protect the joints resulting from the reflowing theconductive connectors 166. In some embodiments, an underfill (not shown)may be formed between the first package 200 and the substrate 400 andsurrounding the conductive connectors 166. The underfill may be formedby a capillary flow process after the package 200 is attached or may beformed by a suitable deposition method before the package 200 isattached.

In the embodiments of FIGS. 1 through 36, a RDL last formation processis illustrated. For example, the redistribution structure 144 is formedover the integrated circuit dies 114 after the integrated circuit dies114 are disposed in the first package 200. In other embodiments, theintegrated circuit dies 114 may be bonded to package features after RDLsare formed (sometimes referred to as an RDL first process). For example,FIGS. 37 through 40 illustrate cross-sectional views of variousintermediary stages of manufacturing a semiconductor package accordingto some alternative embodiments.

In FIG. 37, the redistribution structure 144 is formed over the carriersubstrate 100 prior to attaching the integrated circuit dies 114. Theprocesses used to form the redistribution structure 144 may besubstantially similar to the processes described in FIGS. 1 through 36where like reference numerals indicate like elements.

After the redistribution structure 144 is formed, conductive pillars 700are formed on the redistribution structure 144 as illustrated by FIG.38. As an example to form conductive pillars 700, a seed layer (notshown) is formed over the redistribution structure 144. In someembodiments, the seed layer is a metal layer, which may be a singlelayer or a composite layer comprising a plurality of sub-layers formedof different materials. In some embodiments, the seed layer comprises atitanium layer and a copper layer over the titanium layer. The seedlayer may be formed using, for example, PVD or the like. A photo resistis then formed and patterned on the seed layer. The photo resist may beformed by spin coating or the like and may be exposed to light forpatterning. The pattern of the photo resist corresponds to theconductive pillars 700. The patterning forms openings through the photoresist to expose the seed layer. A conductive material is formed in theopenings of the photo resist and on the exposed portions of the seedlayer. The conductive material may be formed by plating, such aselectroplating or electroless plating, or the like. The conductivematerial may comprise a metal, like copper, titanium, tungsten,aluminum, or the like. Then, the photo resist and portions of the seedlayer on which the conductive material is not formed are removed. Thephoto resist may be removed by an acceptable ashing or strippingprocess, such as using an oxygen plasma or the like. Once the photoresist is removed, exposed portions of the seed layer are removed, suchas by using an acceptable etching process, such as by wet or dryetching. The remaining portions of the seed layer and conductivematerial form the conductive pillars 700.

In FIG. 39, the integrated circuit dies 114 are bonded to theredistribution structure 144 using a suitable bonding process, such asflip chip bonding. The integrated circuit dies 114 may be bonded to theconductive pillars 700 using conductive connectors 702. The conductiveconnectors 702 may comprise microbumps (-thumps), C4 bumps, BGA balls,or the like. The integrated circuit dies 114 may include similarfeatures as described above with respect to the integrated circuit dies114 of FIG. 4 where like reference numerals indicate like elements.

Subsequently, in FIG. 40, an encapsulant 704 is formed on the variouscomponents. The encapsulant 704 may be a molding compound, epoxy, or thelike, and may be applied by compression molding, transfer molding, orthe like. The encapsulant 704 may be dispensed around the integratedcircuit 114 and between the integrated circuit die 114 and theredistribution structure 144. After curing, the encapsulant 704 canoptionally undergo a grinding process to expose the integrated circuitdies 114. In some embodiments, the grinding may be omitted. After theencapsulant 704 is formed, various features may be debonded from thecarrier 100, and a singulation process may be applied along scribe lines(e.g., disposed between adjacent package regions 600 and 602).Conductive connectors (not shown) may be formed on an opposing side ofthe redistribution structure 144 (e.g., on the metallization pattern132). The conductive connectors may be used to bond the singulatedpackage to other package features, such as other integrated circuitdies, device packages, package substrates, interposers, motherboards,combinations thereof, or the like.

Thus, as described above, various embodiments provide methods of formingconductive features, such as conductive lines and/or vias, inredistribution structures of a semiconductor package. Embodimentprocesses may form conductive vias using a photo resist to define apattern of the conductive vias. Because the photo resist is subsequentlyremoved after the conductive vias are formed, the selection of amaterial for the photo resist is not limited to dielectric materialssuitable for inclusion in a finished packet. For example, the materialof the photo resist may be selected to support relatively highresolution lithography, which allows for fine-pitched conductive vias tobe formed. An embodiment conductive via may have a width of about 1 μmor less although vias of other dimensions may also be formed. After thephoto resist is removed, a dielectric layer is formed around the vias,and the dielectric layer's material is selected to provide structuralsupport and insulation to a redistribution pattern disposed therein.Although the dielectric layer may also comprise a photosensitivematerial, the dielectric layer may not support as high a resolutionpatterning as the photo resist used to define the conductive vias.Therefore, various embodiments may provide one or more of the followingnon-limiting advantages: smaller conductive vias by using a higherresolution photoresist to define a shape of the conductive vias; lowermanufacturing cost; reduced polymer layer resolution window issues;improved planarity in redistribution layers; increased metallizationpattern density; and the like.

In accordance with an embodiment, a method includes forming a patternedfirst photo resist over a seed layer. A first opening in the patternedfirst photo resist exposes the seed layer. The method further includesplating a first conductive material in the first opening on the seedlayer, removing the patterned first photo resist, and after removing thepatterned first photo resist, forming a patterned second photo resistover and along sidewalls of the first conductive material. A secondopening in the patterned second photo resist exposes a portion of thefirst conductive material. The method further includes plating a secondconductive material in the second opening on the first conductivematerial, removing the patterned second photo resist, and after removingthe patterned second photo resist, removing exposed portions of the seedlayer. The method further includes depositing a dielectric layer aroundthe first conductive material and the second conductive material.

In accordance with another embodiment, a method includes encapsulatingan integrated circuit die in an encapsulant, depositing a first photoresist over the encapsulant and the integrated circuit die, patterning afirst opening in the first photo resist to expose a first conductivematerial, and plating a conductive via in the first opening. Theconductive via is electrically connected to the integrated circuit die.The method further includes removing the first photo resist anddepositing a first polymer layer around the conductive via. The firstpolymer layer and the first photo resist comprise different materials.The first photo resist supports higher resolution lithography than thefirst polymer layer. The method further includes planarizing the firstpolymer layer so that top surface of the first polymer layer and theconductive via are substantially level.

In accordance with yet another embodiment, a semiconductor packageincludes an integrated circuit die, an encapsulant disposed around theintegrated circuit die, a through via extending through the encapsulant,and a redistribution structure over the integrated circuit die and theencapsulant. A metallization pattern of the redistribution structureincludes a conductive line disposed in a dielectric layer andelectrically connected to the integrated circuit die. The dielectriclayer contacts a top surface of the encapsulant. The metallizationpattern further includes a conductive via over and electricallyconnected to the conductive line. A top surface of the conductive via issubstantially level with a top surface of the dielectric layer.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method comprising: forming a patterned firstphoto resist over a seed layer, wherein a first opening in the patternedfirst photo resist exposes the seed layer; plating a first conductivematerial in the first opening on the seed layer; removing the patternedfirst photo resist; after removing the patterned first photo resist,forming a patterned second photo resist over and along sidewalls of thefirst conductive material, wherein a second opening in the patternedsecond photo resist exposes a portion of the first conductive material;plating a second conductive material in the second opening on the firstconductive material; removing the patterned second photo resist; afterremoving the patterned second photo resist, removing exposed portions ofthe seed layer; and depositing a dielectric layer around the firstconductive material and the second conductive material.
 2. The method ofclaim 1 further comprising planarizing the dielectric layer so that atop surface of the dielectric layer is substantially level with a topsurface of the second conductive material.
 3. The method of claim 1,wherein a photosensitive material of the patterned second photo resistis disposed between a bottom surface of the second conductive materialand the seed layer.
 4. The method of claim 1, wherein the second openingfurther exposes a portion of the seed layer.
 5. The method of claim 1further comprising depositing the seed layer over an integrated circuitdie and on an encapsulant encapsulating the integrated circuit die. 6.The method of claim 1 further comprising: depositing the seed layer overa carrier substrate; and after depositing the dielectric layer, bondingan integrated circuit die over the dielectric layer using a flip chipbonding process.
 7. The method of claim 6 further comprisingencapsulating the integrated circuit die, wherein encapsulating theintegrated circuit die comprises dispensing an encapsulant between abottom surface of the integrated circuit die and the dielectric layer.8. The method of claim 1, wherein the dielectric layer comprises aphotosensitive polymer, and wherein the patterned second photo resistsupports a higher resolution lithography process than the photosensitivepolymer.
 9. A method comprising: encapsulating an integrated circuit diein an encapsulant; depositing a first photo resist over the encapsulantand the integrated circuit die; patterning a first opening in the firstphoto resist to expose a first conductive material; plating a conductivevia in the first opening, wherein the conductive via is electricallyconnected to the integrated circuit die; removing the first photoresist; depositing a first polymer layer around the conductive via,wherein the first polymer layer and the first photo resist comprisedifferent materials; and planarizing the first polymer layer so that topsurface of the first polymer layer and the conductive via aresubstantially level.
 10. The method of claim 9, wherein the firstconductive material is a conductive line, wherein depositing the firstpolymer layer further comprises depositing the first polymer layer alongsidewalls of the conductive line.
 11. The method of claim 10 furthercomprising: depositing a second photo resist over the integrated circuitdie and the encapsulant; patterning a second opening in the second photoresist; plating the conductive line in the second opening, wherein theconductive line is electrically connected to the integrated circuit die;and removing the second photo resist, wherein the first photo resist isdeposited after the second photo resist is removed.
 12. The method ofclaim 9, wherein depositing the first polymer layer comprises depositinga portion of the first polymer layer under a bottom surface of theconductive via.
 13. The method of claim 9, wherein the first conductivematerial is a first seed layer, and wherein the method furthercomprises: after planarizing the first polymer layer, depositing asecond seed layer over the first polymer layer and the conductive via;depositing a second photo resist over the second seed layer; patterninga second opening in the second photo resist exposing the second seedlayer; plating a conductive line in the second opening and electricallyconnected to the conductive via; and depositing a second polymer layeraround the conductive line.
 14. The method of claim 13 furthercomprising planarizing the second polymer layer so that top surface ofthe second polymer layer and the conductive line are substantiallylevel.
 15. A semiconductor package comprising: an integrated circuitdie; an encapsulant disposed around the integrated circuit die; athrough via extending through the encapsulant; and a redistributionstructure over the integrated circuit die and the encapsulant, wherein ametallization pattern of the redistribution structure comprises: aconductive line disposed in a dielectric layer and electricallyconnected to the integrated circuit die, wherein the dielectric layercontacts a top surface of the encapsulant; and a conductive via over andelectrically connected to the conductive line, wherein a top surface ofthe conductive via is substantially level with a top surface of thedielectric layer.
 16. The semiconductor package of claim 15, wherein aportion of the dielectric layer is disposed under a bottom surface ofthe conductive via.
 17. The semiconductor package of claim 15, wherein aline extending along a sidewall of the conductive line also extendsalong a sidewall of the conductive via.
 18. The semiconductor package ofclaim 15, wherein bottom surfaces of the dielectric layer and theconductive line are substantially level, and wherein no other conductivefeatures are disposed between the dielectric layer and the encapsulantalong a line perpendicular to the top surface of the dielectric layer.19. The semiconductor package of claim 15, wherein an additionalmetallization pattern of the redistribution structure comprises anadditional conductive line forming an interface with the top surface ofthe conductive via.
 20. The semiconductor package of claim 15, whereinthe conductive line comprises a seed layer under a conductive material,and wherein a top surface of the seed layer is substantially co-planar.